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Portable cord sizing #78056 08/13/01 07:43 AM
Joined: Mar 2001
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Redsy Offline OP
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I occasionally wire portable pumps with self-contained 3 ph. starters mounted on the unit. They are fed by plugging into 20 amp branch ckts. A typical size is 1.5 HP (3 amps @ 480 volt). Article 400-13(OC protection for the cords) refers to 240-4. 240-4(a) requires OC protection in accordance with the cords ampacity per table 400-5(A), which requires 12 gauge cord for 20 amps. However, 240-4 allows supplementary OC protection as in 241-10 to protect the cord. Is the OL relay in the starter considered to be this supplementary OC protection, and therefoe, can I use cord smaller than #12, based on OL heater size?

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Re: Portable cord sizing #78057 08/13/01 07:26 PM
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sparky Offline
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Redsy;
I'm reading 430-6 The 2nd sentence refers to 400-5, and then ends up in the usual motor tables.
430-22 still applies
of interest,430-42(c) shows a 15 A 99' change

Re: Portable cord sizing #78058 08/13/01 08:13 PM
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Redsy Offline OP
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Sparky,
Thanks. But I'm still hung up on supplementary OC protection as mentioned in 240-4(a). This would allow me to use 14/4 or even 16/4, instead of 12/4 to supply the starter. Remember, it's pulling less than 3 amps, so voltage drop shouldn't be much of a problem. If I can use smaller cable, I'd like to. We usually put about 35' of cord on the pump, and 12/4 can be a nuisance for the operators.

Re: Portable cord sizing #78059 08/13/01 09:15 PM
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sparky Offline
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ok,
210-4(a) does refer to 400-5.
240-9 would seem to side with you here.
I was looking for some reference in 430, to either code loop there or 'amend' the loop out.
I guess i'm still sittin' the fence here [Linked Image]

Re: Portable cord sizing #78060 08/14/01 07:31 AM
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Redsy Offline OP
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Thanks, sparky.
I like 240-9. It was right in front of my eyes, but I didn't see it.

Re: Portable cord sizing #78061 08/14/01 07:17 PM
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sparky Offline
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Well i've gone back and forth here, seems you got a winner.
Lemme play devil's advocate... [Linked Image]
Suppose you had a setup with an adjustable setup, like those new Furnace jobs that can 'dial-in' what you need.
Per code that setting can be played with, so would we size to the upper limit of the range???
[Linked Image]

Re: Portable cord sizing #78062 08/14/01 08:40 PM
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Anonymous
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> would we size to the upper limit of the range???
I should think so unless you can otherwise securely limit the maximum.

Re: Portable cord sizing #78063 08/14/01 10:06 PM
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Redsy Offline OP
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Quote
Originally posted by sparky:
Well i've gone back and forth here, seems you got a winner.
Lemme play devil's advocate... [Linked Image]
Suppose you had a setup with an adjustable setup, like those new Furnace jobs that can 'dial-in' what you need.
Per code that setting can be played with, so would we size to the upper limit of the range???
[Linked Image]

I have 2 of those animals(Smart OL Relay?) on the shelf right now. Allen-Bradley, though. I'm home now, but I recall that even thuogh they are adjustable, you have to choose from a few different ranges for each size starter. This narrows it down somewhat. So, even adjusting all the way up, you won't be going very far for a given relay.


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